Using select for packet sockets - linux

Question

Is it possible to use select for packet sockets? I mean whether its necessary for the socket to be connection-based in order to use select function on it properly?
I'm seeing that the behavior of a socket which I got it by the following socket function call:
int socket_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
is not as I expect. For example, I see that a ping packet which is 60 bytes long when received and read into a 20 bytes length buffer, it waits about a second between each recv function call. I used recvfrom and it didn't help. For this, I ask whether it's correct to use select for a packet socket?
Update
I'm going to include the code to discuss about it:
int MakeBridge(const char *if1, const char *if2)
{
int sock[2];
sock[0] = OpenSocket(if1);
sock[1] = OpenSocket(if2);
int activity;
char buf[20];
const int numSocks = 2;
int nfds = sock[0];
for (int i = 1; i < numSocks; i++)
if (sock[i] > nfds)
nfds = sock[i];
nfds++;
while (true)
{
FD_ZERO(&readfds);
for (int i = 0; i < numSocks; i++)
FD_SET(sock[i], &readfds);
activity = select(nfds, &readfds, NULL, NULL, NULL);
if (activity == -1) // sockets closed
break;
for (int i = 0; i < numSocks; i++)
if (FD_ISSET(_sock[i], &readfds))
{
int len;
CHECK(ioctl(_sock[i], FIONREAD, &len) != -1, "%s", strerror(errno));
printf("socket %d is set\n", i);
printf("total bytes available to read: %d\n", len);
CHECK(len > 0, "");
do
{
int n = min(len, sizeof(buf));
int nbr = recvfrom(_sock[i], buf, n, 0, NULL, NULL);
printf("n %d nbr %d\n", n, nbr);
CHECK(n == nbr, "");
len -= n;
} while (len);
}
}
return 0;
}
Update 2
Not going to segment messages and using large enough buffer makes the code as follows:
// This is a program which is going to make the bridge between two interfaces. brctl is going to be replaced by this program.
#define Uses_CHECK
#define Uses_close
#define Uses_errno
#define Uses_ETH_P_ALL
#define Uses_FD_SET
#define Uses_htons
#define Uses_ifreq
#define Uses_ioctl
#define Uses_printf
#define Uses_signal
#define Uses_sockaddr_ll
#define Uses_socket
#define Uses_strerror
#include <general.dep>
int _sock[2];
int _CtrlCHandler()
{
printf(" terminating...\n");
CHECK(close(_sock[0]) != -1, "");
CHECK(close(_sock[1]) != -1, "");
printf("all sockets closed successfully.\n");
}
void CtrlCHandler(int dummy)
{
_CtrlCHandler();
}
int OpenSocket(const char *ifname)
{
// getting socket
int socket_fd = socket(PF_PACKET, SOCK_RAW/*|SOCK_NONBLOCK*/, htons(ETH_P_ALL));
CHECK(socket_fd != -1, "%s", strerror(errno));
// init interface options struct with the interface name
struct ifreq if_options;
memset(&if_options, 0, sizeof(struct ifreq));
strncpy(if_options.ifr_name, ifname, sizeof(if_options.ifr_name) - 1);
if_options.ifr_name[sizeof(if_options.ifr_name) - 1] = 0;
// enable promiscuous mode
CHECK(ioctl(socket_fd, SIOCGIFFLAGS, &if_options) != -1, "%s", strerror(errno));
if_options.ifr_flags |= IFF_PROMISC;
CHECK(ioctl(socket_fd, SIOCSIFFLAGS, &if_options) != -1, "%s", strerror(errno));
// get interface index
CHECK(ioctl(socket_fd, SIOCGIFINDEX, &if_options) != -1, "%s", strerror(errno));
// bind socket to the interface
struct sockaddr_ll my_addr;
memset(&my_addr, 0, sizeof(my_addr));
my_addr.sll_family = AF_PACKET;
my_addr.sll_ifindex = if_options.ifr_ifindex;
CHECK(bind(socket_fd, (struct sockaddr *)&my_addr, sizeof(my_addr)) != -1, "%s", strerror(errno));
// socket is ready
return socket_fd;
}
int MakeBridge(const char *if1, const char *if2)
{
_sock[0] = OpenSocket(if1);
CHECK_NO_MSG(_sock[0]);
_sock[1] = OpenSocket(if2);
CHECK_NO_MSG(_sock[1]);
printf("sockets %d and %d opened successfully\n", _sock[0], _sock[1]);
fd_set readfds, orig;
int activity;
char buf[1<<16];
signal(SIGINT, CtrlCHandler);
int packetNumber = 0;
const int numSocks = _countof(_sock);
int nfds = _sock[0];
for (int i = 1; i < numSocks; i++)
if (_sock[i] > nfds)
nfds = _sock[i];
nfds++;
FD_ZERO(&orig);
for (int i = 0; i < numSocks; i++)
FD_SET(_sock[i], &orig);
while (true)
{
readfds = orig;
activity = select(nfds, &readfds, NULL, NULL, NULL);
if (activity == -1) // sockets closed
break;
CHECK(activity > 0, "");
for (int i = 0; i < numSocks; i++)
if (FD_ISSET(_sock[i], &readfds))
{
int len = recvfrom(_sock[i], buf, sizeof(buf), MSG_TRUNC, NULL, NULL);
CHECK(len > 0, "");
CHECK(len <= sizeof(buf), "small size buffer");
printf("%10d %d %d\n", ++packetNumber, i, len);
CHECK(sendto(_sock[!i], buf, len, 0, NULL, 0) == len, "");
}
}
return 0;
}
int Usage(int argc, const char *argv[])
{
printf("Usage: %s <if1> <if2>\n", argv[0]);
printf("Bridges two interfaces with the names specified.\n");
return 0;
}
int main(int argc, const char *argv[])
{
if (argc != 3)
return Usage(argc, argv);
CHECK_NO_MSG(MakeBridge(argv[1], argv[2]));
return 0;
}